C# Signature:

[DllImport("user32.dll")]

[return: MarshalAs(UnmanagedType.Bool)] static extern bool EnumChildWindows(IntPtr hwndParent, EnumWindowsProc lpEnumFunc, IntPtr lParam);

public delegate bool Win32Callback(IntPtr hwnd, IntPtr lParam);

[DllImport("user32.Dll")] [return: MarshalAs(UnmanagedType.Bool)] public static extern bool EnumChildWindows(IntPtr parentHandle, Win32Callback callback,IntPtr lParam);

VB.NET Signature:

<DllImport("user32.dll", CharSet:=CharSet.Auto)> _

Private Shared Function EnumChildWindows(ByVal hWndParent As System.IntPtr, ByVal lpEnumFunc As EnumWindowsProc, ByVal lParam As Integer) As Boolean End Function

User-Defined Types:

Notes:

The corresponding unmanaged return type is a 4-byte Win32 'BOOL', so mark the method with the MarshalAsAttribute(.Bool).

Tips & Tricks:

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Sample Code (C#):

    [DllImport("user32")]

    [return: MarshalAs(UnmanagedType.Bool)]     public static extern bool EnumChildWindows(IntPtr window, EnumWindowProc callback, IntPtr i);     /// <summary>     /// Returns a list of child windows     /// </summary>     /// <param name="parent">Parent of the windows to return</param>     /// <returns>List of child windows</returns>     public static List<IntPtr> GetChildWindows(IntPtr parent)     {     List<IntPtr> result = new List<IntPtr>();     GCHandle listHandle = GCHandle.Alloc(result);     try     {         EnumWindowProc childProc = new EnumWindowProc(EnumWindow);         EnumChildWindows(parent, childProc, GCHandle.ToIntPtr(listHandle));     }     finally     {         if (listHandle.IsAllocated)         listHandle.Free();     }     return result;     }     /// <summary>     /// Callback method to be used when enumerating windows.     /// </summary>     /// <param name="handle">Handle of the next window</param>     /// <param name="pointer">Pointer to a GCHandle that holds a reference to the list to fill</param>     /// <returns>True to continue the enumeration, false to bail</returns>     private static bool EnumWindow(IntPtr handle, IntPtr pointer)     {     GCHandle gch = GCHandle.FromIntPtr(pointer);     List<IntPtr> list = gch.Target as List<IntPtr>;     if (list == null)     {         throw new InvalidCastException("GCHandle Target could not be cast as List<IntPtr>");     }     list.Add(handle);     //  You can modify this to check to see if you want to cancel the operation, then return a null here     return true;     }     /// <summary>     /// Delegate for the EnumChildWindows method     /// </summary>     /// <param name="hWnd">Window handle</param>     /// <param name="parameter">Caller-defined variable; we use it for a pointer to our list</param>     /// <returns>True to continue enumerating, false to bail.</returns>     public delegate bool EnumWindowProc(IntPtr hWnd, IntPtr parameter);

Sample Code (VB.net):

    Imports System.Runtime.InteropServices

    Public Class NativeMethods     <DllImport("User32.dll")> _     Private Shared Function EnumChildWindows _         (ByVal WindowHandle As IntPtr, ByVal Callback As EnumWindowProcess, _         ByVal lParam As IntPtr) As Boolean     End Function     Public Delegate Function EnumWindowProcess(ByVal Handle As IntPtr, ByVal Parameter As IntPtr) As Boolean     Public Shared Function GetChildWindows(ByVal ParentHandle As IntPtr) As IntPtr()         Dim ChildrenList As New List(Of IntPtr)         Dim ListHandle As GCHandle = GCHandle.Alloc(ChildrenList)         Try         EnumChildWindows(ParentHandle, AddressOf EnumWindow, GCHandle.ToIntPtr(ListHandle))         Finally         If ListHandle.IsAllocated Then ListHandle.Free()         End Try         Return ChildrenList.ToArray     End Function     Private Shared Function EnumWindow(ByVal Handle As IntPtr, ByVal Parameter As IntPtr) As Boolean         Dim ChildrenList As List(Of IntPtr) = GCHandle.FromIntPtr(Parameter).Target         If ChildrenList Is Nothing Then Throw New Exception("GCHandle Target could not be cast as List(Of IntPtr)")         ChildrenList.Add(Handle)         Return True     End Function     End Class

Alternative Managed API:

The project () provides a

method ManagedWinapi.SystemWindow.FilterDescendantWindows().